1. Field of the Invention
The present invention relates to a pipe connection having a reshaped pipe, a screw fitting body having an internal cone, a union nut, which may be screwed onto the screw fitting body, having an internal clamping face, which, in the operating state of the pipe connection, works together with a retention face of a retention bulge of the pipe, which is produced facing away from the pipe end by reshaping and projects outward radially beyond the external mantle surface of the pipe, and having an adapter ring, which is supported on the side facing toward the screw fitting body using a conical clamping face in the internal cone of the screw fitting body, a radially running front face of the pipe having the same cross-section as the remaining pipe outside the retention bulge.
2. Description of the Related Art
A pipe connection of this type is known from German Patent Application 10 2005 026 580.4. A support ring is situated here in such a way that it is supported by diametrically opposite conical faces on one side on the internal cone of the screw fitting body and on the other side on the internal clamping face of the union nut. The support ring simultaneously presses against a retention face of the retention bulge of the pipe and against the mantle surface of the pipe itself, to fix the pipe in the axial direction in this way. The front face of the pipe partially extends radially inward into the cross-section of the through hole of the screw fitting body and reduces the internal diameter of the pipe connection in this area. This pipe connection has the disadvantage that due to the pipe projecting into the internal diameter, eddies are caused in the medium flowing through the pipe, which occur in particular in the event of small internal diameters. The result of this is a high energy loss in the flowing medium. Furthermore, this pipe connection has the disadvantage that the projections into the internal diameter of a pipeline formed by the pipe and the eddies accompanying them cause a large amount of noise to be developed.
Other types of pipe connections are also known from the prior art. A known pipe screw fitting connection is the “flange pipe screw fitting connection ABO 37° ” from Eifler Maschinenbau GmbH, Euskirchen, in which the reshaped pipe is not equipped with a bulge, however, but rather is expanded into a tulip flare at one end and is held in its position by an additional support ring. An adapter is interposed between the screw fitting body and the pipe, which is equipped on both sides with conical clamping faces, which are adapted to the internal cone of the screw fitting body or to the internal cone formed by the interior of the conical tulip flare, respectively. The adapter thus forms a transition from the 24° cone of the screw fitting body to the 37° flare connection of the pipe. The adapter also typically projects slightly into the internal cross-section of the pipe connection here, because of which the above-mentioned disadvantages may occur.
Furthermore, a connection system for extremely high-pressure proof pipe screw fitting connections having a standardized 24° screw fitting body is known from DE 40 34 803 A1. The end of the pipe to be connected to the screw fitting body is either flared (FIG. 1 of DE 40 34 803 A1) or provided with a flange connected to the pipe end in one piece, which is equipped in one case (FIG. 2 of DE 40 34 803 A1) with a radial front face and in another case (FIG. 3 of DE 40 34 803 A1) with a front face in the form of a spherical cap. In all cases, however, the free cross-sectional area of the pipe end is expanded radially outward in cross-section in relation to the cross-section of the pipe in the remaining pipe outside the connection area. Therefore, there is sufficient space for a sealing ring which is situated in the area of the front side of the pipe end and is mounted inside the corresponding front side of the adapter ring in a groove.
Furthermore, pipe screw fittings are also known from DE 197 23 344 A1 and DE-GM 74 31 646 U1, in which a cutting ring and/or a clamping ring is used, which works together with the non-deformed external mantle surface of the pipe end. In these known screw fittings, adapter rings are also provided to produce a transition to a screw fitting body. However, with cutting ring and/or clamping ring screw fittings, the danger exists in principle that after they have been loosened once starting from the operating state, they will not fulfill their sealing function properly and reliably again when retightened.